Process for making sulfur chlorid



R. E GEGENHEIMER AND M MMHANQ PROCESS FOR MAKING SULFUR CHLQRHJuAPPLICATION FIIED DEC.28,1918.

Emma May25, 192w,

INVENTORS B! mwm ATTORNEY RALPH E. GEGENHEIMER AND MAX MAURAN, 0FNIAGARA FALLS, NEW YORK, ASSIGNORS TO THE MATI-IIESON ALKALI WORKS(INC.), OF PROVIDENCE, RHODE ISLAND, CORPORATION OIE VIRGINIA.

PROCESS FOR MAKING SULFUR CHLORID.

1,34MAL23.

Specification of Letters Patent.

Application filed December 2a, 1918. $eria1 no. 268,602.

ful Improvements in Processes for Making Sulfur Chlorid, o f which thefollowing is a specification.

This invention relates to the production of the monoand di-chlorids ofsulfur, or either of them as desired, and has for its principal objectthe effecting of this production in a simple and more efficient mannerthan, to the best of our knowledge, has been i I i exothermic one; butmbeginning the operapossible hitherto.

We have also aimed to produce the desired product preferablycontinuously and, when desired, in a particularly pure state; thecontamination of the so called monochlorid, S GI by the presence thereinof the d1 clilorid of sulfur, being substantially el1m1- 'nated, if puremonochlorid be the product sought. These and other objects of ourinvention will be hereinafter referred to and the novel combinations ofsteps 111 the process and of means and'elements in the apparatus throughthe intermediacy of which said process may be effected, will be moreparticularly pointed out in the claims appended hereto.

In the accompanying drawing, wh1ch forms a part hereof, we haveexempllfied a preferred arrangement of such apparatus; but as we areaware of various changes and modifications which may be made herein andin the mode of eifectuating our novel process, without departing fromthe spirit of our invention, we desire to be limited only by the scopeof saidclaims, broadly interpreted in the light of our disclosure.

Referring to said drawlng, in which like reference characters designatelike parts in the respective views:

Figure 1 is a diagrammatic representation of an apparatus in and bymeans of whlch, substantially pure sulfur chlorid may be efficiently andcontinuously produced.

Fig. 2 is a detail section of a part of said apparatus, taken on the hneIIII of Fig. 1; fragments only of the steam heated, melt ing pan gridsbeing shown, for convenience of illustration.

As shown in said figures, dry chlorin said grid, onto the lower one.

gas, either pure, or as is commercially practicable and cheaper, mixedwith air in the proportion of, say, 90 per cent. of chlorin to 10 percent. of air,--is supplied by the plpe 1 tothe annular header ordistributer 2.

A' series of pipes 3 depend from the dis tributer or ring casting 2,into the still 4; the chlorin emerging from said pipes, pref- PatentedllIay 25;, 192@. I

erably, well down within :a sulfur containing bath '5. In the preferredconstruction, a series of plugs 6 are provided in the distributer,'topermit of a rod being thrust down therethrough in the event of any ofpipes f3 becoming plugged.

The reaction effectedin the still 4 is an which is a valve 11, tocontrol the flow of H molten sulfur out of the melting pan 12. In thelatter are two steam heated grids, formed of pipes, 13 and 14; the uppergrid having more space between its pipes than the lower,-to allow thesmaller pieces of sulfur, initially introduced intothe pan, or producedby the melting down of the larger lumps reposing upon grid 13, to fallthrough The lower grid lei: is preferably maintained partly or whollyimmersed in the layer of molten su-lfur 15, in the bottom of the pan,and sulfur may be flowed into the bottom of the still, as needed, byopening the valve 11. To prevent the sulfur from congealing in thisvalve or in its pipe.10,I prefer to cover such parts with heatinsulating material 16, such as asbestos, magnesia, or the like. Thestill is provided with suitable means, such as the float controlledindicator 17, for determin' ing the level of the bath; as, desirably,this is maintained well below the top of the water jacket.

More or less mingled with the charge of molten sulfur in the still, is aquantity of sulfur chlorid, or in some cases a mixture of sulfurChlorids; the purpose of which will be hereinafter explained. This slfur chlorid is preferably introduced initi llv;

layer of this material present; since, during the course of theoperation, sulfur will dissolve in the liquid sulfur chlorid, while somesulfur (especially at the higher temperatures indicated, which yield asa product 'Inonochlorid of sulfur containing free sulfur dissolvedtherein) will distil out of the bath and,depending upon the temperaturesemployed,will condense, more or less,

in the upper part of the still, and fall back into the bath, toredissolve or re-distil when its temperature again rises. This actionwill proceed substantially continuously, and hence, normally, no line ofdemarcation between the sulfur and the sulfur chlorid will exist.

Surrounding the still above the steam jacket and extending up,preferably above the level of bath 5, is a water jacket 18, the flow ofwater through which is controlled by the valve 19in the water inletpipe; the wastewater passing out via pipe 20.

Aconduit 21 conveys the gaseous reaction products, normally continuouslyevolved during the operation, together with any air present, up to theinclined header 22, which in turn delivers to the condenser 23. This ispreferably of the water-cooled, surface type; water being introducedthrough the pipe 24 and passing out by Way of pipe 25, whereby to coolthe coil 23.

The condensed sulfur chlorid is deposited. in the storage tank 26, andis drawn off,-

from time to time or continuously, as desired, by means ofthe pipe 27and its valve 28.

At the left hand end of the tank, as viewed in Fig. 1, is a connection29 leading up to a reflux condenser 30. The coil 30 in this condensermay be water or brine cooled; pipe 31 and 32 respectively permittingingress and egress of the cooling fluid.

If the chlorin introduced into the system throughpipe 1, were pure, or,in other words, free from air, this reflux condenser would not benecessary; but since the chlorin supplynormally contains from 5 to 10per cent. of air onaccount of the cost of pure chlorin, We prefer toprovide the condenser 30, to trap any vapors which might, be swept fromthe storage tank along with the air. The colder that this refluxcondenser is maintained, the lower will be the partial pressure ofsulfur chlorid in the exit mixture, and hence the less will be the lossof sulfur chlorid From the condenser 30, the gases pass via pipe 33, toa scrubber 34, which may be of any design. Preferably it comprises atank filled with caustic soda or milk of lime; the pipe leading from thereflux condenser, passing down into the liquor and the escaping gasesbubbling up through the latter to cause any remaining sulfur chlorinvapor to be trapped. Only pure air therefore passes to the suction pump35 which is connected to the scrubber and maintains a partial vacuum inthe whole system.

If the chlorin supplied through pipe 1 were under pressure, pump 35would, of course be unnecessary; but we prefer to operate thesystemunder a partial vacuum, especially whenusing chlorin admixed with air,because such operation is less objectionable if leaks, by any accident,happen to develop in the apparatus; while, further, a smaller pump canbe used than when operating the system under pressure. 0n the otherhand, pressure has its advantages, since with the system under pressurethe partial pressure of sulfur chlorid vapor in the mixture is less thanwith the system under partial vacuum and therefore less care need be exercised in preventing loss of S CL.

As proper control of the temperature of the exothermically reactingcharge and gaseous product or products in the still, is es sential, weprovide a thermometer 36 in the still head; said thermometer beingpreferably disposed as shown.

At the bottom of the still is a valve 37; the purpose of which will behereinafter mentioned.

The operation of the system and mode of conducting the process may nowbe briefly described.

Let us assume that molten sulfur has been introduced into the still fromthe melting pan, preferably until the lower ends of the pipes 3 areimmersed therein; this sulfur being covered by a mass of sulfur chlorid,previously introduced, or sulfur chlorid and sulfur residually presentfrom the pre vious operation of said still.

v At such time steam will, of course, be flowing through the jacket 7,to maintain the sulfur bath molten.

A dry mixture of, say, 92 per cent. chlorin and 8 per cent. air is thenflowed through the conduit 1 and thence down through the As soon as theexothermic reaction is well under way, the steam valve 8 is closed andthe temperature of the still is thereafter controlled by regulating theflow and temperature of the water admitted to the water jacket pastvalve 19. k

This temperature control is most important and the combination thereofwith the provision of a bath into which the current, or preferablycurrents, of chlorin are directed, for intimate contact, first with thatportion of the bath most rich in sulfur and the temperature of the gasespassing off from the still aids in the maintenance of proper reactionconditions within the still, with the result that when we wish toproduce "sulfur" monochlorid alone, we obtain this product continuouslyand free from excess of chlorin and sulfur; instead of having to becontent with the delivery to the condenser of a mixture of sulfurchlorids.

Indeed, in all other methods with which we are acquainted, the sulfurchlorid, especially in continuous processes, is either produced 'mixedwith the dichlorid; or the monochlorid is supercharged with sulfur andthen trickled down through towers, or the like, and chlorinated to thedesired degree.

In no case,'he retofore, has it been possible to effect chlorination ofthe sulfur, exactly to sulfur monochlorid, on but a single pass of theliquor through a single piece of apparatus.

This, we'believe is rendered possible by h a and due 1n very largemeasure to the tem-' perature control; since some action is still goingon in the sulfur chlorid vapors from the time that said vapors leave thelevel of the bath 5 in the still, almost to the time that they reach thepoint where the thermometcr 36 is located.

The novel bath 5, of the described constitution, is important, becausewe have observed that when the chlorin is delivered through pipes 3, forexampleyto a bath of sulfur alone, very little chlorid is formed; thebulk of the gas passing off from the still, remaining chlorin.

T'Vhile a chlorid containing bath might be allowed to gradually buildup, such an operation would, of course, be tedious and mits of thewithdrawal of any residue that may accumulate, due to the use of sulfurcontaining slight impurities.

The product formed is condensed in the surface condenser 23 and collectsin the tank 26, from which it may be withdrawn through pipe 27.Substantially all uncondensed chlorid is condensed in the refluxcondenser, so that, normally, but mere traces remain to be collected inthe scrubber 34.

By means of the just described apparatus, the process may be effectuatedto produce either pure monochlorid of sulfur or any desired mixture ofsulfur monochlorid and sulfur, or of the monochlorid and dichlorid; thischange in product being effected by varying the following factors:

1.-Depth of sulfurIS Cl in the still.

2.-Rate of flow of chlorin.

3.Regulation of temperature. by vary ing the rate of flow andtemperature of water supplied to the jacket 18 of the still.

For example; To obtain pure sulfur monochlorid, S CI one may proceed asdescribed in the foregoing, maintaining the depth of S+S Cl in the stillequal to from about one half to three quarters of the total depth of thestill, and varying the rate of flow of the incoming chlorin gas while atthe same time controlling the temperature until the temperature in thestill head, indicated by the thermometer 36, is 138% To obtain mixturescontaining the monochlorid substantially free from, the diehlorid butcontaining any specified amount of dissolved sulfur (such mixtures beingdesired by the rubber trade), we shut off the cool-J ing water, whollyor in part, as needed, and, if necessary, insulate the still, in orderthat the heat of the reaction may cause distillation of sulfur alongwith the sulfur chlorid; determining at the still head .by, in effect,calibrating the thermometer 36,-what temperature at that point will givethe particular composition of distillate desired. Thus, for example, aproduct containing- 5% dissolved sulfur was obtained in the apparatusgiven by way of illustration, when the temperature of the vapor in theupper end of pipe 31, was allowed to reach 225 C.

If the dichlorid be desired, practically any specific mixture may beobtained by decreasing the depth of S}-S. ,Cl in the still, or byincreasing the rate of flow of the in-" coming chlorin, or both; whilemaintaining the cooling water conditions such that the temperature atthe still head corresponds to that which, in an apparatus of givendimensions and with a given depth of bath in its still and a given rateof flow of chlorin thereinto, will yield the particular mixture ofmonochlorid and dichlorid, desired. These rates for any given product ofparticular consistency, will, of course, depend upon the size ofapparatus employed, etc; but may, obviously, be readily determined bythose skilled in the art, in view of the disclosure herein.

In conclusion, we desire to particularly emphasize the fact that whilechlorin gas acts comparatively slowly upon a bath of molten sulfuralone,if S cl be present in said bath, some of the sulfur dissolvesthere- 'in and this dissolved sulfur then reacts very rapidly with thechlorin bubbling up therethrough.

As the reaction proceeds, the temperature of the molten sulfur is raised.by the heat of the exothermic reaction, beyond the boiling pointof-sulfur monochlorid, so that subsequent reactions may take placebetween sulfur chlorid vapor, sulfur vapor and chlorin,partly whilethese gaseous substances are bubbling up through the molten mass, andpartly inthe vapor filled space above the sulfur containing bath andbelow the condenser. Furthermore, it should be noted, as a markedeconomy of operation, that the heat evolved by this exothermic reactionis the heat which permits us to distil off the desired product.

Having thus what we claim is: 1. The process of making monochlorid ofsulfur which comprises, treating with free chlorin a deep bathcomprising a chlorid of sulfur in contact with molten sulfur, to effectan exothermic reaction in said bath,

described our invention,

and regulating the temperature of said bath and of the gaseous reactionproducts emerging therefrom, to cause the sulfur bearing constituent ofsaid products to consist substantially solely of sulfur monochlorid.

2. The process of making a chlorid of sulfur which comprises, treatingwith free chlorin a bath comprising monochlorid of sulfur having sulfurdissolved therein, by injecting gaseous chlorin into said bath andallowing the reaction gases to then bubble up through said bath, coolingsaid bath to remove a part of the heat developed by said reaction,collecting the vapors which escape from said bath, regulating the temperature of said vapors to produce the product sought, and condensingsaid product. I

3. ,The process of making monochlorid of sulfur which comprises,injecting a mixture of air and chlorin into a bath containing sulfurdissolved in sulfur monochlorid, collecting the gaseous reactionproducts and regulating the temperature thereof to cause the chlorinbearing constituent of said products to exist substantially solely asthe mono- -chlorid of sulfur by the time that they have traversed adetermined distance from said bath, and then condensing the so producedmonochlorid and separating the air therefrom.

at. The process of making monochlorid of sulfur which comprisesproducing said monochlorid in the gaseous phase, substantially free fromsulfur dichlorid, by efi'ecting but a single passage of gaseousmaterial, which includes free chlorin, through a sulfur supplying bath,to combine said chlorin and sulfur by an exothermic reaction, andremoving heat from said bath and from the gaseous reaction productescaping therefrom through a conduit, to an extent sufficient tomaintain the temperature of said product at about 140 C. at a point insaid conduit relatively adjacent said bath but sufliciently distanttherefrom to permit ofthe stabilization of said product.

5. The process of making monochlorid of sulfur which comprisesestablishing a flow of material in the gaseous phase through a closedsystem in substantially all parts of which a partial vacuum ismaintained, said gaseous material initially containing free chlorin,reacting upon said free chlorin to combine sulfur therewith, convertingany dichlorid of sulfur formed during the course of said reaction, tothe monochlorid of sulfur by temperature regulation while a part atleast of said dichlorid is in the gaseous phase, and separating saidmonochlorid of.

sulfur from the remainder of said gaseous material by converting saidmonochlorid to the liquid phase thereof.

6. The process of making monochlorid of sulfur which comprises injectinggaseous chlorin-into a bath containing both a chlorid of sulfur and freesulfur, to effect an exothermic reaction by combining said sulfur andchlorin, while utilizing the heaKe'volved by said reaction, to vaporizethe chlorin bearing products of said reaction and also some of saidsulfur, and reacting upon said vaporized products with said vaporizedsul-- fur to form the product sought.

7. The process of making a chlorid of sulfur which comprises treatingwith gaseous chlorin, a chlorid of sulfur in which is dissolved freesulfur, to exothermically combine said chlorin and sulfur, whileutilizing the heat evolved by the exothermic reaction, to vaporize theproduct of said reaction and regulating the temperature of the so'formed vapor to control the content of said desired chlorid of sulfurtherein.

8. The process of making monochlorid of sulfur which comprises formingsaid monochlorid by combining free chlorin and free sulfur in thepresence of liquid sulfur chlorid, while controlling the temperature ofthe reaction to practically at once yield the product soughtsubstantially free from sulfur dichlorid, said temperature beingmaintained in excess of 130 C.

9. The process of making monochlor-id of sulfur which comprisessubstantially uninterruptedly forming said monochlorid by bubbling agaseous current comprising free chlorin continuously up through a bathcontaining free sulfur dissolved in liquid sulfur chlorid, Wh1lecontrolling the temperature of the reaction to continuously yield

